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AUSCERT External Security Bulletin Redistribution
ESB-2006.0709 -- [Win][UNIX/Linux]
OpenSSH 4.4 released
5 October 2006
AusCERT Security Bulletin Summary
Operating System: UNIX variants (UNIX, Linux, OSX)
Impact: Denial of Service
Execute Arbitrary Code/Commands
CVE Names: CVE-2006-5051 CVE-2006-4924
Revision History: October 5 2006: Added CVE-2006-5051 and CVE-2006-4924
September 28 2006: Initial Release
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OpenSSH 4.4 has just been released. It will be available from the
mirrors listed at http://www.openssh.com/ shortly.
OpenSSH is a 100% complete SSH protocol version 1.3, 1.5 and 2.0
implementation and includes sftp client and server support.
Once again, we would like to thank the OpenSSH community for their
continued support of the project, especially those who contributed
code or patches, reported bugs, tested snapshots and purchased
T-shirts or posters.
T-shirt, poster and CD sales directly support the project. Pictures
and more information can be found at:
For international orders use http://https.openbsd.org/cgi-bin/order
and for European orders, use http://https.openbsd.org/cgi-bin/order.eu
Changes since OpenSSH 4.3:
Security bugs resolved in this release:
* Fix a pre-authentication denial of service found by Tavis Ormandy,
that would cause sshd(8) to spin until the login grace time
* Fix an unsafe signal hander reported by Mark Dowd. The signal
handler was vulnerable to a race condition that could be exploited
to perform a pre-authentication denial of service. On portable
OpenSSH, this vulnerability could theoretically lead to
pre-authentication remote code execution if GSSAPI authentication
is enabled, but the likelihood of successful exploitation appears
* On portable OpenSSH, fix a GSSAPI authentication abort that could
be used to determine the validity of usernames on some platforms.
This release includes the following new functionality and fixes:
* Implemented conditional configuration in sshd_config(5) using the
"Match" directive. This allows some configuration options to be
selectively overridden if specific criteria (based on user, group,
hostname and/or address) are met. So far a useful subset of post-
authentication options are supported and more are expected to be
added in future releases.
* Add support for Diffie-Hellman group exchange key agreement with a
final hash of SHA256.
* Added a "ForceCommand" directive to sshd_config(5). Similar to the
command="..." option accepted in ~/.ssh/authorized_keys, this forces
the execution of the specified command regardless of what the user
requested. This is very useful in conjunction with the new "Match"
* Add a "PermitOpen" directive to sshd_config(5). This mirrors the
permitopen="..." authorized_keys option, allowing fine-grained
control over the port-forwardings that a user is allowed to
* Add optional logging of transactions to sftp-server(8).
* ssh(1) will now record port numbers for hosts stored in
~/.ssh/authorized_keys when a non-standard port has been requested.
* Add an "ExitOnForwardFailure" option to cause ssh(1) to exit (with
a non-zero exit code) when requested port forwardings could not be
* Extend sshd_config(5) "SubSystem" declarations to allow the
specification of command-line arguments.
* Replacement of all integer overflow susceptible invocations of
malloc(3) and realloc(3) with overflow-checking equivalents.
* Many manpage fixes and improvements
* New portable OpenSSH-specific features:
- Add optional support for SELinux, controlled using the
--with-selinux configure option (experimental)
- Add optional support for Solaris process contracts, enabled
using the --with-solaris-contracts configure option (experimental)
This option will also include SMF metadata in Solaris packages
built using the "make package" target
- Add optional support for OpenSSL hardware accelerators (engines),
enabled using the --with-ssl-engine configure option.
* Bugs from http://bugzilla.mindrot.org fixed:
#482 - readconf doesn't accept paths with spaces in them.
#906 - syslog messages from sshd [net] lost.
#975 - Kerberos authentication timing can leak information
about account validity.
#981 - Flow stop in SSH2.
#1102 - C program 'write' with zero length hangs.
#1129 - sshd hangs for command-only invocations due to
#1131 - error "buffer_append_space:alloc not supported"
#1138 - Passphrase asked for (but ignored) if key file permissions
#1156 - Closes connection after C-c is pressed on QNX.
#1157 - ssh-keygen doesn't handle DOS line breaks.
#1159 - %u and %h not handled in IdentityFile.
#1161 - scp -r fails.
#1162 - Inappropriate sequence of syslog messages.
#1166 - openssh-4.3p1 has some issues compiling.
#1171 - configure can't always figure out LLONG_MAX..
#1173 - scp reports lost connection for very large files.
#1177 - Incorrect sshrc file location in Makefile.in.
#1179 - sshd incorrectly rejects connections due to IP options.
#1181 - configure should detect when openssl-0.9.8x needs -ldl.
#1186 - ssh tries multiple times to open unprotected keys.
#1188 - keyboard-interactive should not allow retry after
#1193 - Open ssh will not allow changing of passwords on usernames
greater than 8 characters..
#1201 - Bind address information is not specified in command line
#1203 - configure.ac is missing an open [.
#1207 - sshd does not clear unsuccessful login count on
#1218 - GSSAPI client code permits SPNEGO usage.
#1221 - Banner only suppressed at log level = QUIET (used to be
at log level < INFO).
* Fixes to memory and file descriptor leaks reported by the Coverity
static analysis tool
* Fixes to inconsistent pointer checks reported by the Stanford
Thanks to everyone who has contributed patches, reported bugs and
- - SHA1 (openssh-4.4.tar.gz) = 2294b5e5a591420aa05ff607c1890ab622ace878
- - SHA1 (openssh-4.4p1.tar.gz) = 6a52b1dee1c2c9862923c0008d201d98a7fd9d6c
- - please read http://www.openssh.com/report.html
OpenSSH is brought to you by Markus Friedl, Niels Provos, Theo de Raadt,
Kevin Steves, Damien Miller, Darren Tucker, Jason McIntyre, Tim Rice and
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